jQuery.extend({
	createUploadIframe:function(id, uri){
		//create frame
		var frameId = 'jUploadFrame' + id;
		var iframeHtml = '<iframe id="' + frameId + '" name="' + frameId + '" style="position:absolute; top:-9999px; left:-9999px"';
		if(window.ActiveXObject){
			if(typeof uri== 'boolean'){
				iframeHtml += ' src="' + 'javascript:false' + '"';
			}else if(typeof uri== 'string'){
				iframeHtml += ' src="' + uri + '"';
			}
		}
		iframeHtml += ' />';
		jQuery(iframeHtml).appendTo(document.body);
		return jQuery('#' + frameId).get(0);
	},
	createUploadForm: function(id,fileElementId,data,fileElement){
		//create form	
		var formId = 'jUploadForm' + id;
		var fileId = 'jUploadFile' + id;
		var form = jQuery('<form  action="" method="POST" name="' + formId + '" id="' + formId + '" enctype="multipart/form-data"></form>');
		if(data){
			for(var i in data){
				jQuery('<input type="hidden" name="' + i + '" value="' + data[i] + '" />').appendTo(form);
			}
		}
		var oldElement;
		if(fileElement == null){
			oldElement = jQuery('#' + fileElementId);
		}else{
			oldElement = fileElement;
		}

		var newElement = jQuery(oldElement).clone();
		jQuery(oldElement).attr('id', fileId);
		jQuery(oldElement).before(newElement);
		jQuery(oldElement).appendTo(form);

		//set attributes
		jQuery(form).css('position', 'absolute');
		jQuery(form).css('top', '-1200px');
		jQuery(form).css('left', '-1200px');
		jQuery(form).appendTo('body');
		return form;
	},
	ajaxFileUpload: function(s){
		// TODO introduce global settings, allowing the client to modify them for all requests, not only timeout
		s = jQuery.extend({}, jQuery.ajaxSettings, s);
		var id = new Date().getTime();
		var form = jQuery.createUploadForm(id, s.fileElementId, (typeof(s.data)=='undefined'?false:s.data),s.fileElement);
		var io = jQuery.createUploadIframe(id, s.secureuri);
		var frameId = 'jUploadFrame' + id;
		var formId = 'jUploadForm' + id;
		// Watch for a new set of requests
		if (s.global && ! jQuery.active++){
			jQuery.event.trigger("ajaxStart");
		}
		var requestDone = false;
		// Create the request object
		var xml = {};
		if (s.global){
			jQuery.event.trigger("ajaxSend", [xml, s]);
		}
		// Wait for a response to come back
		var uploadCallback = function(isTimeout){
			var io = document.getElementById(frameId);
			try{			
				if(io.contentWindow){
					xml.responseText = io.contentWindow.document.body?io.contentWindow.document.body.innerHTML:null;
					xml.responseXML = io.contentWindow.document.XMLDocument?io.contentWindow.document.XMLDocument:io.contentWindow.document;
				}else if(io.contentDocument){
					xml.responseText = io.contentDocument.document.body?io.contentDocument.document.body.innerHTML:null;
					xml.responseXML = io.contentDocument.document.XMLDocument?io.contentDocument.document.XMLDocument:io.contentDocument.document;
				}
			}catch(e){
				jQuery.handleError(s, xml, null, e);
			}
			if(xml || isTimeout == "timeout"){
				requestDone = true;
				var status;
				try{
					status = isTimeout != "timeout" ? "success" : "error";
					// Make sure that the request was successful or notmodified
					if(status != "error"){
						// process the data (runs the xml through httpData regardless of callback)
						var data = jQuery.uploadHttpData(xml, s.dataType);    
						// If a local callback was specified, fire it and pass it the data
						if(s.success){
							s.success(data, status);
						}
						
						// Fire the global callback
						if(s.global){
							jQuery.event.trigger("ajaxSuccess", [xml, s]);
						}
					}else{
						jQuery.handleError(s, xml, status);
					}
				}catch(e){
					status = "error";
					jQuery.handleError(s, xml, status, e);
				}
				// The request was completed
				if(s.global){
					jQuery.event.trigger("ajaxComplete", [xml, s]);
				}
				// Handle the global AJAX counter
				if (s.global && ! --jQuery.active){
					jQuery.event.trigger("ajaxStop");
				}
				
				// Process result
				if (s.complete){
					s.complete(xml, status);
				}
				jQuery(io).unbind();
				setTimeout(function(){
					try{
						jQuery(io).remove();
						jQuery(form).remove();
					}catch(e){
						jQuery.handleError(s, xml, null, e);
					}
				}, 100);
				xml = null;
			}
		};
		// Timeout checker
		if (s.timeout > 0){
			setTimeout(function(){
				// Check to see if the request is still happening
				if(!requestDone){
					uploadCallback("timeout");
				}
			}, s.timeout);
		}try{
			var form = jQuery('#' + formId);
			jQuery(form).attr('action', s.url);
			jQuery(form).attr('method', 'POST');
			jQuery(form).attr('target', frameId);
			if(form.encoding){
				jQuery(form).attr('encoding', 'multipart/form-data');
			}else{
				jQuery(form).attr('enctype', 'multipart/form-data');
			}
			jQuery(form).submit();
		}catch(e){
			jQuery.handleError(s, xml, null, e);
		}
		
		jQuery('#' + frameId).load(uploadCallback);
		return {abort:function(){
			try{
				jQuery('#' + frameId).remove();
				jQuery(form).remove();
			}catch(e){}
		}};
	},
	uploadHttpData: function(r, type){
		var data = !type;
		data = type == "xml" || data ? r.responseXML : r.responseText;
		// If the type is "script", eval it in global context
		if (type == "script"){
			jQuery.globalEval(data);
		}
		// Get the JavaScript object, if JSON is used.
		if (type == "json"){
			eval("data = " + data);
		}
		// evaluate scripts within html
		if (type == "html"){
			jQuery("<div>").html(data).evalScripts();
		}
		return data;
	},
	handleError:function(s, xml, status, e){
		// If a local callback was specified, fire it
		if (s.error){
			s.error(xml, status, e);
		}
		// Fire the global callback
		if (s.global){
			jQuery.event.trigger("ajaxError", [xml, s, e]);
		}
	}
});